The invention concerns a means for applying lubricant to the workpiece and/or the working surface of the punch of a multi-stage forging press for the non-cutting forming of metal workpieces having a die, a reciprocatingly driven punch located coaxial to and opposite the die and a holding pin movably mounted in a central bore of the punch.
It is well known to those skilled in the art that wear and deformation of the punch of a forming press can occur in the non-cutting forming of metal workpieces. When the forming operation is intense giving a thin-walled pressing, these undesirable phenomena can appear after only a low number of workpieces has been machined. They lead to a considerable lowering of the surface quality of the workpieces, which must subsequently go through an expensive further machining operation.
The use of a lubricating liquid or an appropriate powder is already the practice on drop forging presses. On this type of press the lubricant, for instance a graphitiferous lubricating liquid, is sprayed onto the workpiece shortly before the punch descends and acts as a separating agent when the punch and workpieces are in contact, ensuring that they detach easily from each other. This protects the contact surfaces of the punch and the workpiece. This method cannot however be applied to automatically operated multi-stage presses which work at a high stroke rate. This limitation is the result of two features of this sort of press. Firstly the rapid periodic motion of the tools would not allow an additional spraying means to be installed, and secondly the lubricant would be carried away by the cooling water, which is sprayed onto the workpiece from all directions, thus not allowing any lubricant to reach the workpiece.
It is therefore the aim of this invention to suggest a means enabling workpieces to be intensively lubricated even on multi-stage forging presses. This is achieved by ensuring in particular that the lubricant is not swept away by cooling water the moment it is applied, but reaches the crucial place, i.e. between the workpiece and the working surface of the punch.